Answer:
24°
Step-by-step explanation:
The sum of all interior angles of a triangle always equal to 180°.
There are two givens in the problem. Set up the equation by equaling 180 to the two given angles and the unknown.
[tex]180 = 102 + 54 + x\\180 = 156 + x\\[/tex]
Isolate x by subtracting 156 to both sides.
[tex]180 - 156 = 156 - 156 + x\\x= 180-156\\x=24\\[/tex]